In association with Dr. Steven Schwartz, who is conducting the Prospective Cardiovascular Health Study, we designed a case-cohort ancillary study to test the hypothesis that the risk of myocardial infarction and/or stroke is associated with elevated plasma levels of homocyst(e)ine and low plasma levels of folate and Vitamins B12 and B6. We also studied whether elevated plasma levels of homocyst(e)ine and Lp(a) interact to increase the risk of myocardial infarction and/or stroke. Results suggest that the combination of elevated plasma homocyst(e)ine and Lp(a) is an extremely strong risk factor for myocardial infarction in young women; we are continuing data collection and specimen analyses in order to further refine our estimate of this association. In combination with supporting laboratory evidence, this finding provides a strong basis for examining the interaction between homocyst(e)ine, Lp(a) and cardiovascular disease risk.